New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1887-10-02

HARD BLUE SAND STONE, CLOSE GRAINED
Tho direct watershed of this reservoir 10 "a
sousre miles but II 10 situated that II can TO-
ceivs thu waste waters from tho adjoining San An
dreas reservoir a. we'll from Pilarcttos both OF
which are In tho nsighborhood and at higher sle'a
tions than this Tho company proposes TO make
this Lower Crystal Springs reservoir the rscepta
Gle not only Of direct and Immediately adjacent
watersheds. but also OF the water shed OF San
Francisquita Creek which has an area OF 20
SQUARE miles, the. Psscadero and San Gregorio
watersheds which have combined area OF 90
square miles, and eventually that OF the Calaverss
watershed which lies the east side OF San FRAN
CISCO Bay and which has an area OF lao square
milea In order to connect the San Frsncisqul'a
watershed with this Crystal Springs watershed
tunne miles long and IL feet clear in diameter IS
to be construc:ed, while IL will take an additional
8 miles tunnel to bring In the Pescadsro and San
Gregor,o watersheds and 2-milss tunnel and ~
miles of pipe to connect the Calaveras watershed
It must be borne In mind that California has
rainy season OF about months ana dry season VI
about 8 IN Jntha As the streams toward the end OF
the dry season run very low and furnish MUS
water IL IL necessary to store the freshet waters
the rainy season tn tide over the denelenoy OF INC
dry season But 40 it has occurred that California
has seen not only dry season but two In succes-
son, it becomes necessary that storage capacity
should b: provided OF sninclsn1 ns 70 grow
ing city like San FRANCISCO and TINS reason mas
caused the Spring Valley Water works TO con-
struot reservoir of these enormous dimensions IN
order not only be safe for the present bat Tor the
near future. ,,,,...
Tho company having entirely prohibited tho cut
ting of timber on the heavily wooded watcr-sheds
and having purchased all watersheds ana
reservoirs they have succeeded 10 keeping all
possl bio Impurities ont Of the water inns the
winter rains which fall on these heavily "ooueu
watersheds form brooks, creeks and 10 some places
torrents. that are oil In turn husoanaed ID tne
OF course In building so large dam as this for
the Lower Crystal Springs reservoir. there WIZ
always be- croakers who will predict the failure OF
tho dam to Withstand tho immense pressure that
will be brought to bear on 1t. Perhaps the best
answer to such doubters Is the ia tn OF the people
who live along the banks OF tho San Mateo canon
and whose places would be swept out OF existence
were this great body of water to rush down upon
them. =.
that this is the largest concrete dam In the world
and that concrete is not In favor with engineers
for such structures. Talks with some OF tho lea1-
ing concrete experts OF San Francisco showed
however that they wore disposed to look on tns
work safe and to see no reason why y snou. .
not be a success One engineer who has had ovei
twenty years experience In concrete worK eao
that he should Law the concrete as monohth, were
he building this dam. There could not % any
material motion Is such q structure and II tnero
was any shrinkage II would DO from the OUTSIDE
to recommend IT. as even these sections never be-
came dry IN the interior. 1t would take SIX
months to thoroughly dry them and fully az much
| time was needed to determine the shrinKage' All
the experts however. agreed that there was o
senseiess prejudice against concrete for such worh
and safety demonstrated by the success OF the 0ig
| dam.